title: An in vivo investigative protocol for HDR prostate brachytherapy using urethral and rectal thermoluminescence dosimetry.
abstract: OBJECTIVE
  To develop an in vivo dosimetry based investigative action level relevant for a corrective protocol for HDR brachytherapy boost treatment.
  
  
  METHODS
  The dose delivered to points within the urethra and rectum was measured using TLD in vivo dosimetry in 56 patients. Comparisons between the urethral and rectal measurements and TPS calculations showed differences, which are related to the relative position of the implant and TLD trains, and allowed shifts of implant position relative to the prostate to be estimated.
  
  
  CONCLUSIONS
  Analysis of rectal dose measurements is consistent with implant movement, which was previously only identified with the urethral data. Shift corrected doses were compared with results from the TPS. Comparison of peak doses to the urethra and rectum has been assessed against the proposed corrective protocol to limit overdosing these critical structures. An initial investigative level of 20% difference between measured and TPS peak dose was established, which corresponds to 1/3 of patients which was practical for the caseload. These patients were assessed resulting in corrective action being applied for one patient. Multiple triggering for selective investigative action is outlined. The use of a single in vivo measurement in the first fraction optimizes patient benefit at acceptable cost.
authors.affiliation: Radiation Oncology Victoria, Melbourne, Australia. wtoye@radoncvic.com.au
authors.forename: Warren
authors.initials: W
authors.lastname: Toye
authors.forename: Ram
authors.initials: R
authors.lastname: Das
authors.forename: Tomas
authors.initials: T
authors.lastname: Kron
authors.forename: Rick
authors.initials: R
authors.lastname: Franich
authors.forename: Peter
authors.initials: P
authors.lastname: Johnston
authors.forename: Gillian
authors.initials: G
authors.lastname: Duchesne
mesh_terms: D001918:Brachytherapy / Q000379:methods* / Q000592:standards; D006801:Humans; D008297:Male; D011471:Prostatic Neoplasms / Q000532:radiotherapy*; D011879:Radiotherapy Dosage; D012007:Rectum / Q000528:radiation effects*; D013819:Thermoluminescent Dosimetry / Q000379:methods*; D014521:Urethra / Q000528:radiation effects*